package com.example.facedetectionjavacv;

import static com.googlecode.javacv.cpp.opencv_core.IPL_DEPTH_8U;
import static com.googlecode.javacv.cpp.opencv_core.cvClearMemStorage;
import static com.googlecode.javacv.cpp.opencv_core.cvGetSeqElem;
import static com.googlecode.javacv.cpp.opencv_core.cvLoad;
import static com.googlecode.javacv.cpp.opencv_objdetect.CV_HAAR_DO_CANNY_PRUNING;
import static com.googlecode.javacv.cpp.opencv_objdetect.cvHaarDetectObjects;

import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.List;

import com.googlecode.javacpp.Loader;
import com.googlecode.javacv.cpp.opencv_objdetect;
import com.googlecode.javacv.cpp.opencv_core.CvMemStorage;
import com.googlecode.javacv.cpp.opencv_core.CvRect;
import com.googlecode.javacv.cpp.opencv_core.CvSeq;
import com.googlecode.javacv.cpp.opencv_core.IplImage;
import com.googlecode.javacv.cpp.opencv_objdetect.CvHaarClassifierCascade;

import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.FrameLayout;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ImageFormat;
import android.graphics.Paint;
import android.hardware.Camera;
import android.hardware.Camera.Size;

public class CameraDetectionActivity extends Activity
{
    private FrameLayout layout;
    private FaceView faceView;
    private Preview mPreview;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
    	super.onCreate(savedInstanceState);
    	// Hide the window title
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

        // Create our Preview view and set it as the content of our activity
        try
        {
            layout = new FrameLayout(this);
            faceView = new FaceView(this);
            mPreview = new Preview(this, faceView);
            layout.addView(mPreview);
            layout.addView(faceView);
            setContentView(layout);
        }
        catch (IOException e)
        {
            e.printStackTrace();
            new AlertDialog.Builder(this).setMessage(e.getMessage()).create().show();
        }
    }
}

// FaceView class
class FaceView extends View implements Camera.PreviewCallback
{
    public static final int SUBSAMPLING_FACTOR = 4;

    private IplImage grayImage;
    private CvHaarClassifierCascade classifier;
    private CvMemStorage storage;
    private CvSeq faces;

    public FaceView(CameraDetectionActivity context) throws IOException
    {
        super(context);

        // Load the classifier file from Java resources
        File classifierFile = Loader.extractResource(getClass(),
        		"/com/example/facedetectionjavacv/haarcascade_frontalface_alt.xml",
        		context.getCacheDir(), "haarcascade_frontalface_alt", ".xml");
        if (classifierFile == null || classifierFile.length() <= 0)
        {
            throw new IOException("Could not extract the classifier file from Java resource.");
        }

        // Preload the opencv_objdetect module to work around a known bug
        Loader.load(opencv_objdetect.class);
        classifier = new CvHaarClassifierCascade(cvLoad(classifierFile.getAbsolutePath()));
        classifierFile.delete();
        if (classifier.isNull())
        {
            throw new IOException("Could not load the classifier file.");
        }
        storage = CvMemStorage.create();
    }

    public void onPreviewFrame(final byte[] data, final Camera camera)
    {
        try
        {
            Camera.Size size = camera.getParameters().getPreviewSize();
            processImage(data, size.width, size.height);
            camera.addCallbackBuffer(data);
        }
        catch (RuntimeException e)
        {
            // The camera has probably just been released, ignore
        }
    }

    @SuppressLint("DrawAllocation")
	protected void processImage(byte[] data, int width, int height)
    {
        // First, downsample our image and convert it into a grayscale IplImage
        int f = SUBSAMPLING_FACTOR;
        if (grayImage == null || grayImage.width() != width / f || grayImage.height() != height / f) {
            grayImage = IplImage.create(width / f, height / f, IPL_DEPTH_8U, 1);
        }
        int imageWidth  = grayImage.width();
        int imageHeight = grayImage.height();
        int dataStride = f * width;
        int imageStride = grayImage.widthStep();
        ByteBuffer imageBuffer = grayImage.getByteBuffer();
        for (int y = 0; y < imageHeight; y++)
        {
            int dataLine = y * dataStride;
            int imageLine = y * imageStride;
            for (int x = 0; x < imageWidth; x++)
            {
                imageBuffer.put(imageLine + x, data[dataLine + f * x]);
            }
        }

        cvClearMemStorage(storage);
        faces = cvHaarDetectObjects(grayImage, classifier, storage, 1.1, 3, CV_HAAR_DO_CANNY_PRUNING);
        postInvalidate();
    }

    @SuppressLint("DrawAllocation")
	@Override
    protected void onDraw(Canvas canvas)
    {
        Paint paint = new Paint();
        paint.setColor(Color.RED);

        if (faces != null)
        {
            paint.setStrokeWidth(2);
            paint.setStyle(Paint.Style.STROKE);
            float scaleX = (float)getWidth() / grayImage.width();
            float scaleY = (float)getHeight() / grayImage.height();
            int total = faces.total();
            for (int i = 0; i < total; i++)
            {
                CvRect r = new CvRect(cvGetSeqElem(faces, i));
                int x = r.x(), y = r.y(), w = r.width(), h = r.height();
                canvas.drawRect(x * scaleX, y * scaleY, (x + w) * scaleX, (y + h) * scaleY, paint);
            }
        }
    }
}

// Preview class
class Preview extends SurfaceView implements SurfaceHolder.Callback
{
    SurfaceHolder mHolder;
    Camera mCamera;
    Camera.PreviewCallback previewCallback;

    @SuppressWarnings("deprecation")
	Preview(Context context, Camera.PreviewCallback previewCallback)
	{
        super(context);
        this.previewCallback = previewCallback;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed
        mHolder = getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void surfaceCreated(SurfaceHolder holder)
    {
        // The Surface has been created, acquire the camera and tell it where to draw
        mCamera = Camera.open();
        try
        {
           mCamera.setPreviewDisplay(holder);
        }
        catch (IOException exception)
        {
            mCamera.release();
            mCamera = null;
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder)
    {
        // Surface will be destroyed when we return, so stop the preview.
        // Because the CameraDevice object is not a shared resource, it's very
        // important to release it when the activity is paused.
        mCamera.stopPreview();
        mCamera.release();
        mCamera = null;
    }
    
    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h)
    {
        final double ASPECT_TOLERANCE = 0.05;
        double targetRatio = (double) w / h;
        if (sizes == null)
        {
        	return null;
        }

        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        // Try to find an size match aspect ratio and size
        for (Size size : sizes)
        {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
        	{
            	continue;
        	}
            if (Math.abs(size.height - targetHeight) < minDiff)
            {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        // Cannot find the one match the aspect ratio, ignore the requirement
        if (optimalSize == null)
        {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes)
            {
                if (Math.abs(size.height - targetHeight) < minDiff)
                {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h)
    {
        // Now that the size is known, set up the camera parameters and begin the preview
        Camera.Parameters parameters = mCamera.getParameters();

        List<Size> sizes = parameters.getSupportedPreviewSizes();
        Size optimalSize = getOptimalPreviewSize(sizes, w, h);
        parameters.setPreviewSize(optimalSize.width, optimalSize.height);

        mCamera.setParameters(parameters);
        if (previewCallback != null)
        {
            mCamera.setPreviewCallbackWithBuffer(previewCallback);
            Camera.Size size = parameters.getPreviewSize();
            byte[] data = new byte[size.width * size.height *
                                   ImageFormat.getBitsPerPixel(parameters.getPreviewFormat()) / 8];
            mCamera.addCallbackBuffer(data);
        }
        mCamera.startPreview();
    }
}